DETROIT (AP) — Maxine Powell, who was responsible for developing the charm, grace and style of Motown Records' artists during the Detroit label's 1960s heyday, died Monday at age 98.

Motown Historical Museum CEO Allen Rawls said Powell died of natural causes at a hospital in Southfield, Mich.

She didn't sing or write songs, but those associated with Motown say Powell was as essential to the label's operations as any performer or producer.

She directed the label's Artists Development Department, also known as "Motown's Finishing School." Through it, she emphasized to many artists — including Smokey Robinson and the Miracles, the Jackson Five and the Supremes — how they should carry themselves, treat people and dress.

Motown founder Berry Gordy said the training school was the only one of its kind offered at any record label.

Powell's passing comes less than two months after she was honored at the museum by Robinson and others.

"She was such an important, integral part of what we were doing here at Motown," Robinson said at the Aug. 26 event held at the famed Hitsville, U.S.A, building.

"It didn't matter who you became during the course of your career — how many hits you had, how well your name was known around the world," he said. "Two days a week when you were back in Detroit you had to go to artists' development. It was mandatory."

Gordy paid tribute to Powell via videotape during the celebration, joking that he still remembered many of Powell's sayings, such as "Do not protrude the buttocks," and "Do not confuse me with your parents — they're stuck with you. I'm not."

"You had style," Gordy said. "You gave them class."

Born in Texarkana, Texas, Powell was raised in Chicago, where she began her career as an actress. She later moved to Detroit, where she opened a finishing and modeling school.

Powell said in August that she would "teach until there's no breath left in my body."

"I love all the Motown artists," she said. "This has been a blessing. I thank God for allowing me to be here."